Weed dynamics and efficiency of weed management practices in productivity of aromatic rice under subtropical Manipur conditions

Abstract

A field investigation was conducted during the kharif seasons of 2021 and 2022 at the Research Farm of the College of Agriculture, Central Agricultural University, Imphal, to assess the impact of integrated weed management practices on weed suppression, growth and yield of indigenous aromatic rice cultivars under rainfed subtropical conditions of Manipur. The experiment was laid out in a split-plot design with four main-plot cultivars—Khamanui Lungra, Chaphemai, Nambew, and Chakhao Poireiton; and five subplot weed control treatments replicated thrice. The weed management strategies comprised manual weeding, Pretilachlor 50% EC as pre-emergence followed by either Metsulfuron methyl + Chlorimuron ethyl or Penoxsulam as post-emergence, Pyrazosulfuron ethyl fb Penoxsulam and an untreated control. Weed dynamics including density was recorded at 30, 60, 90 and 120 days after transplanting (DAT), while weed control efficiency (WCE), weed index (WI), growth attributes and yield parameters were assessed throughout the crop season. The sequential application of Pretilachlor fb Penoxsulam (W3) proved most effective, achieving the highest weed control efficiency (89.21%), the lowest weed index (9.37%) and significant suppression of both grassy and broad-leaved weeds across all crop stages. Among the cultivars, Chaphemai exhibited superior growth performance in terms of plant height, number of tillers and dry matter production, which translated into the highest grain yield (4.69 t/ha). In contrast, the untreated control resulted in poor crop performance due to unchecked weed interference. The study highlights the importance of integrating cultivar competitiveness with sequential herbicide application as an efficient and sustainable weed management approach to enhance the productivity and profitability of transplanted aromatic rice in Northeast India.